What are the major mechanical themes in the set according to your vision?
Attachments (Auras + Equipment)

Please present six common cards of a color different from the color in the second round pitch. These cards should clearly demonstrate at least one major mechanical theme of the set.

This is an idea I cooked up back in February or somewhere, I forget. I tried to design an Aura set and failed to get past the white commons, so I will just copy and paste the relevant parts here. I hope you have time to read through this.

A. The plane of Elrin.

B. A mana-comet destroyed civilization on Elrin, and the natives are prepared to take back their land.

C. Elrin was once a normal plane like any other. filled with great cities and technological advances. However, a comet of pure mana hit the plane, and that led to the collapse of Elrin's civilizations altogether. Elrin today is a post-apocalyptic world where the creatures were persecuted and driven to extinction (beasts, insects, horrors) have returned from hiding, and are prepared to take back their native land. However, with so much mana in one central area, they cannot live peacefully, and will be driven to civil war. Meanwhile, the survivors from the mana-comet are coming back, with the same technological advances. The natives, however, have another weapon of theirs that they will be utilizing - beings of pure mana.

D. Mechanics:
Manifest: Manifest represents the spectacular mana in the world taking shape. Auras can either enchant an existing creature, boosting it significantly, or take shape on its own. Manifest appears as a white-only mechanic, as white is the only being of mana selfless enough to buff other creatures.
Knowledge: Knowledge represents the civilization trying to fend off the natives and rebuild their civilization. As a minority, they have developed great stamina and new ways to fight back. Knowledge represents the civilization inventing new ways to smite the natives. Knowledge appears in blue and red, with small numbers in other colors.
Reclaim: The horrors of black and red are a minority race, and they had to find new ways to survive. Because they were descendants of the phoenix, the horrors have found new ways to revive after they die.
Totem Armor: Totem Armor returns in this set. It will appear in white and green.
Transform: Transform returns in this set as a way to represent "wispmagic", a form of magic that is not extinguished after they have been cast, and creatures that transform into auras (mounts)
Aura Swap: Aura Swap appears in small amounts.

Colors:
White: White is home to many of the beings of pure mana in the plane, as well as the many kinds of birds that populate Elrin. Totem Armor appears here.
Blue: Blue is represented by the calculating and cold humans trying to get back their plane. They use wispmagic, a trait shared with green.
Black: Black is filled with horrors utilizing the reclaim mechanic. Black has insects as well (sharing with Green).
Red: Red also employs horrors, but the human warlords, scattered across Elrin, are red too.
Green: Green has strong aura-creatures (mounts), beasts, and insects. Totem Armor also appears here. Wispmagic is shared with blue.

Okay, so basically, the plane was ruled by humans a long time ago, and then a huge mana-comet crashed onto the plane and wiped out all human civilization. Then, the native creatures (beasts, birds, insects, horrors, phoenixes) returned to the plane after being persecuted and almost driven to extinction. Then, the creatures have a civil war, and the surviving humans (based in U and R) try to claim their land back. The mana-beings (stylized as elementals) are the neutral race in this conflict and could be the "good guys" in the set, aiding both humans and creatures.

I'm going to showcase "the humans" in this set. The blue humans are a drastic departure of the W humans we see in Innistrad - they are cold and ambitious, with the grandiose goal of reclaiming the plane. The red humans are bands of surviving humans, needing a role model to look up to. There are several packs of humans ruled by warlords in the plane, only concerned for their survival. I believe that Time Spiral did not hit upon the post-apocalyptic theme well enough with the time shenanigans, and this is a chance to bring it back in a new light with an aura + equipment backdrop.

The humans focus on equipment, auras (more minor than the creatures though), and knowledge. Do you mind if I break the rules a bit?

…and I realized that I used knowledge already in my Ekkremes submission. :( Wispmagic is basically transform auras and not going to be used in this submission.

I felt that this pitch had too many weird things going on at once. It contains many elements that people can't understand without a detailed explanation, like mana creatures from a mana comet, oppressed vermin-folk, and a high-tech society that suffered an apocalypse. It would be impossible to get this across through just cards; you would need to write a novel.

Some set premises like "A world made of metal" or "A world that has been split into 5 worlds, each missing some elements" were very weird, innovative premises, but despite that fact, the themes got across very easily. I think the key is in how you mix the known and the unknown. People know what a world is, and people know what metal is. They may have never thought about a world made of metal before in their lives, but once they hear that idea they can start picturing it and be intrigued. But if it's something like a "mana comet," the meaning of that is completely dependent on whatever attributes and back story you assigned to that thing, and there's no way for people to register what that means, unlike "a world made of metal." If a set is going to have a weird element that needs explanation, I believe that a) it should focus on just one of those elements and b) it should be possible to register that element on an emotional level, without knowing the full explanation for those things. For example, you can understand Shadowmoore is in a dark, nighmarish world, without knowing that it's a world that alternates between a sunshine world and a nighmare world. You can understand that Eldrazi are giant world-destroying monsters and have an emotional reaction to that.